golf mk4 gti 2.0 poor idle high emissions

[sparkyjohn2005]

help! my golf gti 2.0 is running really rough idleing and is putting out high emissions also guzzling fuel took out the spark plugs which were just replaced and were pretty sooty changed the coolant temp sensor but made no differance can anyone tell me whats wrong?

[Crasher]

A fault code read may indicate a faulty lambda sensor (very common on this engine) but the problem can be caused by a faulty Air Mass Meter (or MAF as some call it) DO NOT DISCONNECT the AMM to test it, that will just store a fault code and not help you. Get a code read done and come back with the results.

[sparkyjohn2005]

ok thanks mate shall i book it in at vw garage or will any auto diagnostics place do?

[Crasher]

Anyone who can read and clear codes. Get a print out.

[angelo4913]

Hi all, i have the same problem as listed above and was wondering if anyone had solved it? any suggestions? i have serviced the car, replaced air flow mass sensor, changed HT leads... bit stuck now as diagnostic does not say what the problem is specifically. just reads: misfire, high emissions etc..

Thanks
Angelo

[Crasher]

What is the car year, engine code and the fault codes you are getting?

[angelo4913]

Hi, it is a 1999, 2.0 golf gti, it has recently come up with emissions workshop, it is running really rough, has very high emissions, getting very poor miles per gallon. it says misfire recognised on snap on diagnostic, but i can not work out what the problem is. i was thinking maybe it was a lambda sensor.?

[Crasher]

Where did the leads come from? Which brand and part number of plug? What is the engine code? These are very prone to coil pack failure, is the fault code clarified as a particular cylinder or just random/multiple. Yes, the lambda sensors on these are very prone to failure but you would have an associated fault code.

[fray]

has this problem being solved? i have the same problem, also got a decat pipe fitted, my car cut out today and showed emmisions on the screen? any help would be great
thanks

[Crasher]

Fitting a decat pipe to a car with a post cat lambda sensor is really stupid. Of course it will show an emissions error, the second sensor is there to monitor the performance of the cat and the signal is also used by the ECU to apply correction valves to the mixture to fine tune the running so that cat is running efficiently. How did the people who did that expect the car to pass an MOT? On the 2.0 8v, removing the cat will give no appreciable power gains whatsoever. You will have to fit a cat and probably two new lambda sensors (or at least the pre cat sensor) and see how it goes from there. The only way to stop it getting upset is to fit a lambda cheater to the post cat sensor input which fools the management system into thinking the cat is still there but it doesn’t get around the legality issue.

[fray]

i did not fit the decat it was like this when i bought it, how would i go about cheating it then as i know i would be looking at a nice bill for a cat and sensors

[Crasher]

I know you didn’t fit it, I gathered that-I was prodding at the numpty who did and sold it to you.

There are post cat lambda cheaters available from the states but that still doesn’t deal with the thorny subject of an MOT.

[angelo4913]

Problem still there, i was told that if it was the coil pack then it would be more noticable when driving more heavily although the problem is more noticable when the car is idling. It goes to almost cut out and finds itself and same again continuously. Emissions are very high and it is very juicy to run at the moment. Emissions workshop came up and the car cut out. Im not sure which step to take next, with it either being coil pack or lambda sensor?

[angelo4913]

...

[Crasher]

Code read before anything else. You need to get it to someone who knows what they are doing on VAG cars.

[angelo4913]

it was put on snap on scanner but there was no error that could help identify what the problem was, it just said misfire recognised...

[Crasher]

Random multiple with no specific cylinder, suggests an over fuelling problem.

Common issues on these are plugs, leads, coil pack, pre cat lambda, air mass meter, dirty throttle body and split intake hose. What is the engine code?

[angelo4913]

everything has been done apart from pre cat lambda and the throttle body, where do i find engine code? im not sure of the top of my head... it lets out black sut out of the exhaust also...

[Crasher]

PM me your reg number.

[Crasher]

It is a 2000 Y chassis model with an APK engine.

If the only code stored was “16684 (P0300) Misfire recognition” and the plugs, leads and coil pack are all new and top quality, then a garage will have to go deeper and check the compressions, look for air leaks etc but I am surprised that is the only code. I have seen lambda sensors cause this code BUT only in conjunction with a lambda code such as 16556 (P0172) Bank 1 fuel metering system too rich.

[GolfGuy1]

First post here, so hi everyone.

Crasher, i've been getting the same problem on the same car/engine (2000 plate 2.0L Mk4 Golf Gti)

The guy at the garage is stumped because he resets the ECU to get it running properly again only for the same problem to return as the OPs to return after a week or so. Had it reset again yesterday and will see how it goes for now.

The Lambda and the MAF sensor were replaced a couple of years ago when the problem first started and he's suggested we try another Lambda probe, then after that the only other thing he can think of is replacing the ECU but that's going to be silly money on a car of this age unless you know of an alternative?

It's a real pain because other than this, the car is Ok even with over 130k on the clock and i'd rather use money for other things at the moment, so was hoping to keep this one for a couple more years if possible.

[Crasher]

If he resets it he will be clearing codes so what are the codes?

[GolfGuy1]

I've no idea TBH but i'll try and get them from him if it'll be of any help.

[Crasher]

It will be a help.

[angelo4913]

Hi again Crasher, i have had another diagnostic test done on the car and the following codes were found:
16518 o2 sensor which was changed yesterday seems to have helped the whole emissions problem
16496 intake air temp sensor not yet done as was not aware,
16486 maf which has already been done few weeks back,
17536 bank 1 mixture adaption: system too lean but i think that this has been solved by changing o2 sensor and
17990 idle speed regulation adaption limit reached not a clue what that is.
sorry and 16555 system too lean bank 1, although i think this has been solved by changing the o2 sensor

By the way it is regarding t reg golf engine code apk.

[GolfGuy1]

Went back to the mechanic to see about the fault codes but everything had been cleared from his system but touch wood, it seems to be ok now after the 2nd reset of the ECU. Someone on here mentioned that the piston design allows a fair bit oil to go out the exhaust and that it can lead to blocking the Lambda sensor.

I've got a feeling that might have been my problem, so and advice of the mechanic i gave the car a decent 60 mile run up the motorway doing 70 in 3rd (5k revs)to get some real heat into the exhaust system and hopefully burn off whatever crap might have been blocking the sensor. Not scientific but it seems to have done the trick - hopefully...

[Crasher]

Angelo, I will try and look into this tomorrow.

[Crasher]

16518 (P0134) Bank 1 probe 1 no activity - Check Lambda probe and Lambda control before catalyst

16496 (P0112) Intake air temperature sender -G42 signal too low- Check intake air temperature sender

16486 (P0102) Air mass meter -G70 signal too low- Check air mass meter and check intake system for leaks

17536 (P1128) Bank 1 mixture adaptation (mult.*) system too lean - Check intake system for leaks

17990 (P1582) Idling speed adaptation limit reached Check intake system for leaks

16555 (P0171) Bank 1 fuel metering system too lean - Check intake system for leaks

* mult. = multiplicative, i.e. fault occurs over the entire engine speed range and at all throttle openings


I think you may be able to see a pattern there. Check the air pipe between the AMM and the throttle body where it goes to thee cam cover breather, they often split and the small vacuum hose there often gets left off. If all appears OK, fit a new genuine VW dealer supplied Air Mass Meter. The air temperature sender G43 is in the AMM and not separately replaceable.

[angelo4913]

The emissions seems to have dropped completely since the lambda sensor was changed but it is booked in at a garage to check on saturday on MOT machine.
After i got a print out of the codes a few days back before lambda sensor was changed they were reset and the car automatically found itself and started to idle properly until the next day when it started to come back... bit confusing init. il check for air leaks tomorrow and see how it goes init.

I think the AMM only came up in the diagnostic because it was not reset after it was changed until 2 days ago, i will see if it comes back when it gets put back on diagnostic on saturday and let you know which codes came back after resetting them few days back.

[GolfGuy1]

Back again!

The last ECU reset lasted about a month, so this time the Mechanic decided it was time to change the Bosch Lambda sensor, fitted around 3 years ago, for an NTK yesterday.

The car's running fine at the moment, so we'll see how it goes from here.

Cheers again.